We have Teamviewer 12 Corporate license.
It offered to try new interface. Clicked yes.
Now I want to revert to my regular Teamviewer 12 interface.
How do I do that?
You have to uninstall 13 and reinstall 12. There will be an option to keep or delete your data during the uninstall.
You'll need to edit one value in your registry to go back to the old interface. You need to navigate in your registry to "HKEY_CURRENT_USER\Software\TeamViewer" and change 'UseNewUI' value from '1' to '0.' Remember to either have Teamviewer shutdown or restart it.
Don't bother with TryNewUICount. That value is just the notification that a new interface is available. If you set that back to '0' then you'll see the notification you can change it to the new interface, but leaving it at '1' keeps it from appearing.